Hawthorns have "real" thorns. Photo by Ted Bodner, Southern Weed Science Society
Hawthorns (Crataegus genus) are small, craggy trees with angular branching reminiscent of bur oaks, but on a small scale. The stout often-branched thorns they sport, which range from one to three inches in length, add to their rugged looks.
The Crataegus genus is a very complex group taxonomically, and experts differ widely even as to the number of hawthorn species, with estimates ranging from two hundred to a thousand. Much of the confusion is due to frequent hybridization, which makes identification difficult. Nonetheless, there are several fairly distinct and popular species available to home owners.
One of my personal favorites is cockspur hawthorn (C. crusgalli), which my husband and I planted in our former suburban yard. The cockspur, a Midwestern favorite, has glossy leaves and branches which swoop
to the ground, setting it apart from other hawthorns. Washington hawthorn (C. phaenopyrum), is popular in the East for its graceful branching structure and resistance to hawthorn rusts. Both have profuse white blossoms in spring, and abundant red fruits and brilliant color in fall.
The black hawthorn (Crataegus douglasii) is a western species found from Alaska and Canada to California and South Dakota, with some isolated populations in the East. As its name suggests, the black hawthorn has black fruits, and it grows in varied woodland and scrub habitats. Although not quite as showy as some hawthorns, it is very hardy, has bright fall color. and is used in landscaping.
Value for birds
Hawthorns' copious spring blossoms draw pollinating insects, which in turn attract both migrating and resident birds. The trees are also favorite nesting sites because of the protection offered by their thick foliage, dense branching, and large thorns. Shrikes find the thorns useful for another reason – they often impale mice and other prey they have captured on the thorns to store them for later eating. Although hawthorn fruits, or "thorn apples," aren't eaten immediately in fall, they provide food for birds in winter, and sometimes even into spring. Caterpillars are preferred by most birds for feeding their young, and for this reason, one of the greatest values of hawthorns may be the many caterpillars they host. Interestingly, one caterpillar has evolved a defense
against bird predators – the blinded sphinx (Paonias excaecatus) makes sure it nibbles every bit of leaf as it feeds, since birds often search for caterpillars by checking leaves
Value for other wildlife
An amazing one hundred and fifty-nine species of eastern caterpillars feed on hawthorn leaves. Among them are some
of our showiest species, including white
admiral and red-spotted purple butterflies and the cecropia moth. Hawthorn fruits are eaten by a variety of mammals.
The black hawthorn has been used as
a source of food for honey bees.
With gorgeous spring flowers, dense summer foliage, bright fall fruits, and picturesque branching structure in winter, hawthorns are outstanding trees in all seasons. They are tough trees, too, which generally do well in coarse gravelly soils, sand or heavy clays, as well as more loamy soils.
Hawthorns prefer open sunny locations, where they develop wide spreading crowns and make excellent specimen trees. Their small size suits them well for small yards,
as well as larger properties.
The main downside is cedar-hawthorn rust, which can cause hawthorns to drop their leaves prematurely. Cedars and hawthorns are alternate hosts for the rust, and should not be planted near one another. However, more resistant hawthorn varieties are available. Although I usually advise against cultivars because they limit genetic diversity, cultivars may be a wise choice in this case. For those concerned about the possibility of young children hurting themselves on the thorns, there are also some thornless cultivars.
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